Bulk storage of liquids such as fuel and water relies for the most part on the use of bulk storage tanks. The bulk storage tanks can be deployed and set up at a location as needed, for example, in a battlefield, to provide a transportable distribution center for the stored substances. These tanks can vary in capacity, for example, from 3,000 gallons to 250,000 gallons, although smaller or larger tanks can be used. The substances stored in these tanks can be critical resources for the safety and lives of the infantry in the battlefield, and the volume of the substances in the tanks are constantly being monitor to ensure an adequate supply of resources is available when needed.
For bulk storage tanks with a rigid or fixed geometry, intrusive techniques such as immersing a level detection instrument into the tank can be used to detect the level of the liquid in the tank. Examples may include immersing a fiber optic cable, capacitive probe, or ultrasonic sensors into the tank. Based on the detected level of the liquid and the fixed tank geometry, the volume of the liquid contained in the tank can be computed. However, these intrusive techniques may require specially designed tanks or modifications to existing tanks. Furthermore, these techniques are suitable only for rigid or fixed geometry tanks, which can be bulky and cumbersome to transport.
For collapsible storage tanks that may not have a rigid or fixed geometry, one way of determining the volume of the substance in such a tank is to measure the height of the collapsible tank, and use a strap table to determine the fluid volume. However, such techniques require the strap table to be calibrated to the particular size and manufacturer of the collapsible tank, and is susceptible to inaccuracies due to changes in temperature. Furthermore, as the flexible tank ages and the material of the flexible tank warps and stretches out, periodic calibration of the strap table is also required. In some scenarios, a poorly calibrated strap table can result in up to a 30% measurement error.
Embodiments of the invention address these and other problems, individually and collectively.